The application relates generally to protection and anti-corrosion coatings on metallic substrates, and specifically to the formation of aluminum oxide coatings on metallic substrates.
The established methods for passivating metallic substrates include conversion coatings and anodizing processes, among other methods. In general, these processes involve the reaction of metal alloy component surfaces with chemical baths to form reaction product layers. Because the quality and integrity of these passivation layers are dependent on the composition and uniformity of the reacting surfaces, these processes can generally only be used on specific types of metallic substrates. Additionally, these processes involve multiple, intensive steps, including cleaning, rinses, and post-sealing treatments, that consume a large amount of water throughout the process, generate hazardous waste and sludge, and deposit a thick, non-uniform layer on the substrate. Many of these processes also require additional deposition of a protective organic coating layer for optimal corrosion resistance.